Device for transporting unstable stacks of sheetlike materials

ABSTRACT

Method and apparatus for use in transporting unstable stacks of sheet material whereby releasably interconnected supports constrain the sides of the stack against slippage and such supports are positioned to provide gaps for passing strapping material about the stack.

This invention relates to an apparatus for transporting unstable stacksof sheetlike material, such as paper, between a device for forming thestack and a strapping device.

In newspaper printing offices, in particular in big plants where moderninstallations are applied, the printing presses usually available inmultiple-have a high production which is received by stacking devicesdirectly adjoining the printing presses and producing stacks of apredetermined number of newspapers. These stacks must move past a numberof strapping devices in order to form packages of newspapers suitable tobe transported to the points of distribution.

The stacks produced by the stacking devices are thereby conveyed viaconveyor belts to the strapping devices. In the course of this operationconsiderable problems regularly arise since the stacks, in particularthe fresh stacks of newspapers, have little stability, not to say nostability, and fall apart on the slightest provocation. The result isthat the transport means between the stacking device and the strappingdevice move very slowly because rapid movements would result in thedisintegration of the stack. Although one has succeeded in raising theproduction capacity of the stacking device and of the strapping devicesufficiently to meet the high production rate of the printing presses,yet the required production capacity is not arrived at because betweenthe stacking device and the strapping device the speed is too low. Sincethe strapping devices may experience periods of standstill, for examplewhen a new stock of tape has to be put in, but the stacking devices,however, continue to produce, the transport arrangements between thestacking devices and the strapping devices are often embodied such as tocreate the possibility of conveying the formed stacks to variousstrapping devices. However, this results in a change of direction whichconsiderably increases the risk of a stack falling apart.

The object of the present invention is to provide a solution for thisproblem which, although it presents itself in particular in the case oftransport of newspapers, also requires a solution in a broader sense.

This object is arrived at according to the invention in that the stackis arranged or formed in a holder or frame supporting at least all sidesof the stack. The result is that in case of an acceleration orretardation respectively the stack remains intact. As a consequence onemay adapt the transport speed between the stacking devices and thestrapping devices to the high speed of operation of said devices and onemay apply change-over devices without any objection so that the stackswhich become available can be supplied to the strapping devices inoperation.

It will be preferred to remove the holder or frame at the strappingdevice in order not to add additional weight to the further transport ofthe newspapers to the distribution stations. It is, however, conceivableto have the frame consist of an envelope of flexible material enclosingthe stack, such as for example a sheet of synthetic material. Such anenvelope is capable of keeping the newspapers of the stack in place, butwill yield when the stack is strapped with the aid of wire-like ortape-like material. If required said envelope may consist of elasticmaterial. However, such envelopes can only be used once and thereforeincrease the cost.

It is to be noted that there are machines that cover the stack withshrink foil extending over the top surface, the bottom surface and twosides. This system is not satisfactory because transport to this machineis required and during transport the foil is not sufficiently firm andgets stuck between moving parts.

It is preferred to use holders or frames which may be used over and overagain. This means that the frames should be constructed such as to allowstrapping. They must therefore present a passage for the strappingmaterial. This is arrived at according to the invention in that theframe consists of a container or box rectangular in top plan view, therigid sides and the bottom (if present) of which are divided accordingto two planes of division of the container extending perpendicularly toone another and the parts of the container are interconnected byengageable and disengageable coupling members. This means that the frameconsists of four parts which can be combined to a container or box butwhich can be separated again at the strapping device and thus may bemoved apart so that space becomes available for allowing the passage ofthe strapping loops. Such engageable and disengageable coupling membersor latches are conceivable in many embodiments. One may use for instancemanually operated latches but within the scope of a high rate ofproduction automatically operated locking means, such as bolts that arereleased by insertion pins, are more suitable. A simple construction isarrived at if one couples the frame parts to one another by means ofmagnets, if particular permanent magnets. These magnets ensure that thecontainer or box constitutes a sufficiently rigid unit to transport thestack of newspapers. At the strapping device the gripping force of themagnets is then eliminated or interrupted which may be done in a simplemanner by moving the frame parts apart with means suitable for thispurpose. According to the invention it is possible to effect this withthe aid of the strapping material itself and for this purpose the edgesof the seams between the frame parts are profiled such that the seamscan be opened by the strapping tape. The strapping material cuts as itwere through the wall of the frame since the magnets ensure that afterthe passing of the strapping material the seam is closed again. Thestrapping devices then produce frames containing a strapped stack. Afterhaving been emptied the frames can be used again. Of course the bottomof the frame, if any, should have a recess in order that the closingmechanism may reach the wire or tape ends to be interconnected.

However, if the frame is equipped with operable locking members, it ispreferred according to the invention to embody said frame such that thefour frame parts defined by the planes of division extendingperpendicularly to one another present a distance between the edgesfacing one another which at least at the side walls is bridged by thelocking members that keep only said parts together and spaced. Thisembodiment is of great importance if the weight of the stack containedin the frame impedes or hampers the moving apart of the frame parts andthis is in particular the case when this moving apart is effected by thestrapping material itself which must temporarily interrupt theconnection consisting for example of magnets. The forces then to beexerted cannot always be brought about with the existing strappingmachines.

This situation is still accentuated if newspapers are involved which atthe strapping device are compressed with the aid of a pressing bar. Thispressing bar will not only compress the stack of newspapers but willalso press the frame bottom firmly against the work table of thestrapping device so that the frame parts cannot easily move apart. Sincethe frame presents continuous interruptions in the form of spacing atthe two planes of division, which are bridged exclusively by the lockingmembers, the result is that after the disengaging of the lockingmembers, at the point where the strapping must be laid, there are noframe parts at all because the strapping can be laid through the gapformed by the spacing directly around the compressed stack.

After completion of the strapping these locking members may easily beengaged again in some manner.

The locking members preferably consist of a locking bolt which isspring-biased and is arranged on one part for cooperation with anoperable pawl and an operable spacer. The pawl is thereby coupled to anarm or pin projecting beyond the upper edge, said arm or pin being urgedby a spring into the locking position. However, another mode ofoperation of the pawl is also conceivable. In case said pawl is operatedagainst the spring action, the locking bolt is released and is retractedunder spring tension into the other part, the spacer beingsimultaneously disengaged. This spacer is necessary because otherwisethe parts are drawn together by the spring acting on the locking bolt.The operation of the pawl may be effected by means of the pressing barwhich reaches the operating members for the pawl at the end of itsworking stroke.

The spacer can be embodied and operated in a manner similar to thelocking bolt. It is preferred to have the spacer coupled to the lockingbolt. This spacer may comprise a pawl provided on the locking bolt andblocking the bolt in the slidout position, the spacer being operated atthe same time with the first-mentioned pawl. However, the spacerpreferably consists of a rod or pin movable parallel to the locking boltin opposite direction, said rod or pin being adapted to be coupled tothe bolt via a gear wheel and a gear rack transmission. Consequentlywhen the locking bolt is unlocked it moves the spacer in the oppositedirection, whereas when the locking bolt is moved again into theoperative position the spacer is also moved into the operative position.

The operation of the locking bolt can be realized in a simple manner byproviding on the locking bolt an outwardly projecting operating pinwhich projects from the side wall in transverse or longitudinaldirection and can be operated by means of stops or by means of operatingmembers to be provided at the strapping device, said operating membersreceiving an operating signal at the end of the strapping cycle.

According to the invention the frame can be a box the side wall parts ofwhich are hinged to the bottom, said side wall parts being alsointerconnected at the corners by engageable and disengageable couplingmembers, such as magnets. Such boxes can be developed in a flat plane,which simplifies their use, since the non-used boxes require littlespace. Furthermore it is possible to apply such boxes with advantage inthe stacking device by forming the stack on a removable support abovethe developed box so that after the forming of the stack and the removalof the support the stack drops onto the developed box. This box ispositioned above an aperture and will move downwards when the side wallssimultaneously fold back. One may also conceive to form the stack on thedeveloped box and to bring about the downward movement with asimultaneous folding back of the sidewalls upon a predetermined weightbeing reached. Also for the purpose of emptying such a box thispossibility of folding open can be very useful.

With the present invention one succeeds in effectively solving the everexisting problem of the transport of newspapers and the like without thenecessity of important changes in the stacking device and strappingdevice respectively. For the transport between said devices one may nowuse modern and rapid transport means. The frames can be made from anysuitable material.

The invention will now be further explained with reference to thedrawings.

FIG. 1 shows in perspective an example of a frame according to theinvention.

FIG. 2 is a top plan view of a frame according to the invention.

FIG. 3 shows in perspective a stack with a flexible enclosure.

FIG. 4 is a section according to the line IV--IV of FIG. 2.

FIGS. 5 and 6 show in perspective views of parts of the frame of FIGS. 1and 2.

FIG. 7 shows in perspective a detail of a frame comprising engaging anddisengaging coupling members.

FIG. 8 shows the frame as embodied according to FIG. 7 in the same wayas FIG. 1 in perspective.

FIG. 9 shows the frame of FIG. 8 in a manner corresponding to FIG. 2.

The frame shown in FIGS. 1 and 2 consists of four parts 1, 2, 3 and 4each consisting of a bottom a and side walls b and c respectively. Theframe is divided according to middle planes of division constituting theseams 5 and 6 respectively and extending perpendicularly to one another.

As indicated in FIG. 4 the vertical side walls of the box may be securedto the bottom with the aid of hinges 7 and 8 and may form a verticalseam 9 in the corners.

It is, however, conceivable to embody each part 1 to 4 incl. such thatbottom 1 and side walls b and c respectively constitute one rigid unit.

At the seams 5 and 6 the parts 1 to 4 incl. fit properly together inthat one part has an edge 10 of V-shaped section and the other part anedge 11 of W-shaped section, magnets 12 and 13 respectively having beenrecessed in said edges. The result of this profiling is that the seamsform an outwardly open V-shaped groove into which the strapping materialcan penetrate which upon tensioning of the strapping loop presses theseparts apart.

Each bottom part 1 also comprises a recess 14. These recesses constitutetogether an aperture for the closing mechanism of the strapping machine.

The frame shown in FIGS. 8 and 9 essentially corresponds to the oneshown in FIGS. 1 and 2, which means that each of the four parts consistsof a bottom part a and two side parts b and c. The side wall parts b andc are connected by means of hinges to the bottom part a in the manner asshown in FIG. 4. In the erected position the coupling of the side wallparts to one another is effected with the aid of permanent magnetsarranged in the corners, as indicated by reference numeral 15. Theembodiment shown in FIGS. 8 and 9 differs from the one according toFIGS. 1 and 2 in that on the edges of parts 21, 22, 23 and 24 there aredistances or gaps 16, 17 which are exclusively bridged by bolts 18 and19 respectively.

FIG. 7 shows a possible embodiment of the locking members. The lockingbolt 19 shown in FIG. 7 is slidable in a recess 20 of a side wall b andis influenced by a tension spring 25 that tries to move the locking bolt19 into the retracted position in which it is positioned with thehook-like end 26 entirely in the corresponding recess 27.

The locking bolt 19 comprises in addition a projecting pin 28 with whichthe bolt 19 can be moved into the operative position as shown.

Instead of in the transverse direction such a pin may also project inthe longitudinal direction of the bolt from the end of the wall b.

The hook-like end 26 of the locking bolt 19 cooperates with a panel 29that is coupled to an operating rod 30 and is held by a spring 31 in theposition holding the locking bolt. When the rod 30 is pressed downwards,the pawl 29 will release the locking bolt 19 so that the latterinterrupts the connection and entirely releases the gap between theedges of the side wall parts b facing one another.

In the embodiment shown the upper edge of the locking bolt 19 isconstructed as a gear rack 32 adapted to cooperate with a gear wheel 33that cooperates with a slidable rod or pin 34 the lower side of which isprovided with teeth.

It will be clear that when the locking bolt 19 is moved to the right bythe gear wheel transmission, the rod or pin 34 is moved towards the leftand is thereby accomodated in the recess 35.

When the locking bolt 19 is slid again into the operative position themeshing of the teeth of the bolt 19 with the gear wheel 33 will causethe rod 34 to be slid out and to form a stop which ensures that theparts of the frame stay apart and therefore the gap between the edgesfacing one another always has the same dimension.

Instead of the locking members shown naturally other embodiments may beconceived. For instance one may conceive locking members that are urgedby springs into the operative position and that are pushed away by thepressing rod or a member secured thereto respectively, returningautomatically into the operative position as soon as the pressing rod islifted again. Also in that case the entire mechanism can be hidden fromview by means of cover plates like 36. With regard to the embodimentshown in FIG. 3 it is to be noted for the sake of completeness that thisFigure depicts a stack of newspapers, the sides of which are enclosed bya comparatively rigid envelope 37 of synthetic material, which, however,is sufficiently flexible to allow a strapping with tape material 38 andon the other hand is not so soft that the stack would not be supported.

I claim:
 1. An apparatus for stabilizing an unstable stack of sheetmaterial to facilitate the transportation thereof, which apparatuscomprises a plurality of releasably interconnected support membersdisposed to engage respective sides of the stack over the height thereofto constrain the sheet material against edgewise slippage, said supportmembers being positioned to provide gaps for passing strapping materialabout the stack, said support members having confronting inclined edgesurfaces that are spreadable apart to establish said gaps when saidsurfaces are engaged by tensioned strapping material.
 2. An apparatusaccording to claim 1 wherein said support members are releasablyinterconnected by means including a spring-biased locking bolt on onesupport member and cooperating with a pawl and spacer means on anothercorresponding support member.
 3. An apparatus according to claim 1wherein said support members include a plurality of aligned pairs ofsupport members each pair disposed along one of four rectangularlyarranged sides of the stack.
 4. An apparatus for stabilizing an unstablestack of sheet material to facilitate the transportation thereof, whichapparatus comprises a plurality of releaseably interconnected supportmembers disposed to engage respective sides of the stack over the heightthereof to constrain the sheet material against edgewise slippage, saidsupport members being positioned to provide gaps for passing strappingmaterial about the stack, and magnetic means on said support members andoperable to releasably interconnect same.